Fire and Manzanita Chaparral in the San Jacinto Mountains, California

Arctostaphylos glandulosa chaparral at 1,019 m (4,000 ft) elevation retained the same vegetational dominants after burning by producing root crown sprouts and/or seedlings. The floristic composition was changed by the appearance of annual species not found in the unburned chaparral. Most, if not all, of these herbs are considered to have arisen from seeds stored in the litter and or/soils. Post—fire succession is similar to that established for the lower elevational chamise (Adenostoma fasciculatum) chaparral, but is more rapid since the temporary herbaceous cover reaches a peak the first year following fire. Post—fire seedling mortality was most evident in Ceanothus spp. Although manzanita and chamise produced prodigious numbers seedlings with burning, these seedlings are suspected of seldom contributing to mature chaparral cover. Shrub distribution patterns and post—fire succession, particularly the appearance of shrub and herbaceous seedlings, may be determined more by the presence or absence of ash and related pH changes than by other factors. Arctostaphylos and Ceanothus seedlings were most numerous on gentle slopes and level sites where a deep ash layer persisted, while Adenostoma seedlings grew on steeper sites where little ash was deposited. Natural fire occurrences are considered to be less frequent than in the lower elevational chamise chaparral and the higher conifer communities, perhaps occurring only once or twice a century.